• 소성∙가공
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• 제10권2호
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• pp.144-150
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• 2001

Tool design is introduced in a multi-stage rectangular cup drawing process with the large aspect ratio. Finite element simulation is carried out to investigate deformation mechanisms with the initial tool design. The analysis reveals that the difference of the drawing ratio and the irregular contact condition produces non-uniform metal flow to cause wrinkling and severe extension. For remedy, the modification guideline is proposed in the design of the tool and process. Analysis results confirm that the modified tool design not only improves the quality of a deep-drawn product but also reduces the possibility of failure.

• Ocean and Polar Research
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• 제44권2호
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• pp.179-190
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• 2022

Data missing in optical satellite images caused by natural variations have been a crucial barrier in observing the status of marine surfaces. Although there have been many attempts to fill the gaps of non-observation, there is little research to analyze the ratio of missing grids to overall sea grids and their seasonal patterns. This report introduces the method of quantifying the distribution of missing points and then shows how the missing points have spatial correlation and seasonal trends. Both temporal and spatial integration methods are compared to assess the effectiveness of reducing missing data. The temporal integration shows more outstanding performance than the spatial integration. Moran's I and K-function with statistical hypothesis testing show that missing grids are clustered and there is a non-random distribution from daily integration. The result of the seasonality test for Moran's I through a periodogram shows dependency on full-year, half-year, and quarter-year periods respectively. These analysis results can be used to deduce appropriate integration periods with permissible estimation errors.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.33-36
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• 2001

In this paper, we have studied the characteristics of wet etching using citric acid based wet etchant. We have used the citric acid / hydrogen peroxide solution, citric acid / hydrogen peroxide / D.I. water solution. From our experimental result, a volumetric 1：3 ratio of citric acid and hydrogen peroxide and 1 ： 3 ： 1 ratio of citric acid, hydrogen peroxide, and D.I. water is shown to be a better wet etchant of PHEMT's system.

• 한국생산제조학회지
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• 제21권2호
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• pp.276-282
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• 2012

This study looked for Mode status of each for fatigue crack growth behavior about the repeat load of mode I and the static load of mode II. The experiment was performed in the state of the repetition frequency of the sine wave 10Hz, the stress ratio 0.1, maximum load 300kg.f, a static load 0, 100, 200, 300kg.f, As the experimental results, in mode of static load, while the load value increases, the crack growth rate is slower as the energy of a crack mixing grows. Mode I and the power mode II get an influence each other in the direction of crack propagation path, but as they eventually get closer to the breaking point of the crack growth, it is dominated by the mode I.

• Nuclear Engineering and Technology
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• 제50권7호
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• pp.1120-1130
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• 2018

An analysis of a pyroprocessing safeguards methodology employing the Pu-to-$^{244}Cm$ ratio is presented. The analysis includes characterization of representative used nuclear fuel assemblies with respect to computed nuclide composition. The nuclide composition data computationally generated is appropriately reformatted to correspond with the material conditions after each step in the head-end stage of pyroprocessing. Uncertainty in the Pu-to-$^{244}Cm$ ratio is evaluated using the Geary-Hinkley transformation method. This is because the Pu-to-$^{244}Cm$ ratio is a Cauchy distribution since it is the ratio of two normally distributed random variables. The calculated uncertainty of the Pu-to-$^{244}Cm$ ratio is propagated through the mass flow stream in the pyroprocessing steps. Finally, the probability of Type-I error for the plutonium Material Unaccounted For (MUF) is evaluated by the hypothesis testing method as a function of the sizes of powder particles and granules, which are dominant parameters to determine the sample size. The results show the probability of Type-I error is occasionally greater than 5%. However, increasing granule sample sizes could surmount the weakness of material accounting because of the non-uniformity of nuclide composition.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.645-646
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• 2011

• 한국분무공학회지
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• 제3권3호
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• pp.23-32
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• 1998

The effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.I. diesel engine. The main factor was the aspect ratio (Bowl Diameter / Bowl Depth) of bowl of combustion chamber, and the cylinder pressure, engine performance and emissions of the engine using the 4 kinds of the combustion chamber were meadured. Also, the combustion characteristics compared of the experimented and the calculated values which is used by the Hiroyasu's combustion model. The results are as follows; The effect of $d_c/H$ on ignition delay period are small. The smoke is corerelated to the heat release of the premixed and the diffusion combustion, i.g, the smoke decreased by decreasing the premixed combustion or increasing the diffusion combustion on cumulative heat release. The premixed combustion process has more effect than the diffusion combustion on smoke. The formal tendency of $d_c/H$ on engine performance has not appear.

• 품질경영학회지
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• 제22권4호
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• pp.1-12
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• 1994

각각의 설계인자들의 실험조건에서 얻어지는 특성치들의 분산은 평균에 영향을 받는다. 많은 경우에 평균이 커짐에 따라서 분산이 커지는 경향이 있다. 다구찌가 산포제어인자를 찾기 위해서 제시한 SN 비인 $(SN)_i$ = 10 log ($\bar{y}_{i}^{2}/s_{i}^{2}$) 은 분산이 평균의 제곱에 비례하여 커지는 경우이다. 그런데 분산이 평균의 제곱보다 더 느리게 또는 더 빠르게 커질 수도 있기 때문에 이 논문에서는 간단한 자료분석적 기법에 의해서 그 관계를 추측하여, 합당한 SN 비를 사용할 것을 제시하였고, 평균조정인자를 찾기위한 통계량인 감도 $(S)_i$ 의 통계적 성질들을 논의하였다.

• 유기물자원화
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• 제22권3호
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• pp.41-52
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• 2014

본 연구에서는 부정기적 발생 오수의 생분해도 특성 parameters를 현장 시료채취 및 분석실험을 실시하여 조사 및 분석하였으며 결과는 다음과 같다. TCODcr (Total CODcr)의 1,2차 평균 농도는 325.5 mg/L 이며 TCOD 분율은 100% 로 분석되었다. SCODcr (Soluble CODcr)의 1,2차 평균 농도 는 135.9 mg/L 이며 TCOD 분율은 41.8% 로 분석되었다. Ss (Readily biodegradable substrate)의 1,2차 평균 농도는 74.1 mg/L 이며 TCOD 분율은 22.8% 이다. $S_I$ (Soluble inert non-biodegradable substrate)의 1,2차 평균 농도는 61.8 mg/L 이며 TCOD 분율은 19.0% 이다. Xs(Slowly Biodegradable Substrate)의 1,2차 평균 농도는 27.8 mg/L 이며 TCOD 분율은 8.5% 이다. $X_H$의 1,2차 평균 농도는 103.4 mg/L 이며 TCOD 분율은 31.8% 이다. $X_I$ (Particulate inert non-biodegradable substrate)의 1,2차 평균 농도는 58.5 mg/L 이며 TCOD 분율은 18.0% 이다. 따라서 대상 시료의 용존성 생분해 가능 유기물질은 41.8%로 분석되었으며, 이중 생분해가 용이한 분율은 22.8%로 나타났다. 이와 같이 부정기적인 유입 유량으로 인한 유량조정 또는 균등조의 운전으로 유입부하 변동폭에 대한 영향은 크지 않을 것으로 판단된다.

• 대한수의학회지
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• 제6권1호
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• pp.18-23
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• 1966

The protein-bound iodine-131, the concentration of iodine-131 in blood, and the excretion rate of I-131 through urine and feces were observed in nine Korean native goats, 3 months age, following administration of $3{\mu}C$ of I-131 per kg of body weight. No signiant differences were found due to sex and castration. 1. The average protein-bound iodine-131 conversion ratio of goats was 16.7% in 24 hours. In castrated group, the lowest proteinbound iodine-131 conversion ratio was observed. 2. The average concentration of iodine-131 in bleed, increased very rapidly by 2 hours(4.75%) and rapidly decreased within 6 hours(0.73%). 3. The average excretion rate of I-131 through urine was highest in 24 hours(19.00%) and decreased rapidly within 48 hours(5.32%). 4. The average excretion ration rate of I-131 though feces was highest in 24 hours(2.55%), and decreased slowly.